Geophysical Research Abstracts, Vol. 8, 01942, 2006 SRef-ID: 1607-7962/gra/EGU06-A-01942
© European Geosciences Union 2006
Proposing a mechanistic understanding of changs in atmospheric CO
2during the last 740,000 years
P. Köhler and H. Fischer
Alfred Wegener Institute for Polar and Marine Research, PO Box 12 01 61, D-27515 Bremerhaven, Germany (pkoehler@awi-bremerhaven.de)
Atmospheric carbon dioxide (CO2) measured in Antarctic ice cores shows a natu- ral variability of 80 to 100 ppmv during the last four glacial cycles and variations of approximately 60 ppmv in the two cycles between 410 and 650 kyr BP. We here (Köhler and Fischer, 2006) use dust and the isotopic temperature proxy deuterium (δD) from the EPICA Dome C Antarctic ice core covering the last 740 kyr together with other paleo-climatic records to force an ocean/atmosphere/biosphere box model of the global carbon cycle in a forward mode over this time in order to reconstruct the natural variability of CO2. Our simulation results covered by our proposed scenario are based on process understanding gained previously for carbon cycle variations dur- ing Termination I (Köhler et al., 2005). They match the CO2measured in the Vostok ice core well (r2= 0.80) and we predict prior to Termination V significantly smaller amplitudes in CO2variations mainly based on a reduced interglacial ocean circulation and reduced interglacial Southern Ocean sea surface temperature. These predictions for the pre-Vostok period match the new CO2data from the EPICA Dome C ice core for the time period 410 to 650 kyr BP equally well (r2 = 0.79). This is the first for- ward modelling approach which covers all major processes acting on the global carbon cycle on glacial/interglacial time scales. The contributions of different processes (ter- restrial carbon storage, sea ice, sea level, ocean temperature, ocean circulation, CaCO3
chemistry, marine biota) are analysed.
References:
Köhler, P., Fischer, H., Munhoven, G., Zeebe, R. E. (2005). Quantitative interpretation of atmospheric carbon records over the last glacial termination, Global Biogeochemi- cal Cycles, 19, GB4020, DOI: 10.1029/2004GB002345.
Köhler, P., Fischer, H. (2006). Proposing a mechanistic understanding of changes in at- mospheric CO2during the last 740 000 years, Climate of the Past Discussions, 2, 1-42.
SRef-ID: 1814-9359/cpd/2006-2-1, http://direct.sref.org/1814-9359/cpd/2006-2-1.
